I'm currently using \longrightarrow to mean "tends to [some limit]", and sometimes I need to use its negation. I see that there is an \nrightarrow, but unfortunately it doesn't make a matching pair with \longrightarrow, and \not\longrightarrow looks quite bad. What's the easiest way to adjust the position of the little slash so that I can define a \nlongrightarrow? The solution from this related question looks excellent but seems to be overkill for my purposes.